While the cable giant is losing TV subscribers, it is more than making up for that with growth in high-speed Internet and voice services.

The fear that consumers will cut the cord in favor of online options has long shadowed Comcast (ticker: CMCSA), the nation's largest cable provider. Yet far from foundering at a time when new technology is pouring into the industry and household formation (a traditional source of subscriber growth) has slowed, Comcast has thrived in recent years, thanks to its Internet offerings...